Remote control systems



Oct. '23, 1956 H. GELB REMOTE CONTROL SYSTEMS 2 She'ets-Sheet 1 Filed April 12, 1951 2mg Gear Solenoid To S's/syn X lx orm fndzcator Spur INVENTOR Herbert Gelb Se/syn Y To SeISyn X S's/syn Z Se/syn Y Mozor 369/. 3

Cran lc Oct. 23, 1956 H. GELB 2,768,339

REMOTE CONTROL SYSTEMS Filed April 12, 1951 2 Sheets-Sheet 2 flepeatr INVENTOR.

. Herbert Gelb T B Motor A lorney United States Patent 2,768,339 REMOTE CONTROL SYSTEMS Application April 12, 1951, Serial No. 220,680 2 Claims. (Cl. 318-18) This invention relates to remote control systems utilizing Selsyn motors.

not be upset by an attempt, accidental or otherwise, to operate the system in the absence of energization therein.

The invention may be utilized to provide a remote control system wherein a transmitter drives an indicator at a home station and a repeater drives mechanism at a distant station. Also the system may be modified so that a motor at a remote station drives both a transmitter and other machinery and a repeater drives an indicator of performance of the motor at a control station.

A particular object of the invention is to provide such a remote control system wherein usual means available for turning the rotor of a transmitter for the purpose of controlling a repeater cannot be operated to vary the angular disposition of the rotor of the transmitter with respect to that of the rotor of the repeater when the common circuit is deenergized.

Another object of the invention is to provide such a system wherein neither the rotor of the transmitter, or that of the repeater, or either rotor, if desired, may be turned when the common circuit is open. In short, this particular object involves the provision of means for positively locking either or both rotors against rotation upon deenergization of the circuit at precisely the angular disposition of either or both rotors obtaining at the moment of deenergization, and for either or both automatically.

Another object of the invention is the provision of means whereby, in such a remote control system, the transmitter may only be turned through the agency of a magnetic clutch, the latter being in circuit therewith so that the circuit must be closed before said means become operable.

Another object of the invention is to provide a remote control system involving a transmitter and a repeater wherein the transmitter drives an indicator by means of a worm so that the rotor of the transmitter cannot accidentally, or otherwise, be turned by means of the indicator, and wherein the repeater drives other mechanism by means of a worm so that the rotor of the repeater cannot accidentally, or otherwise, be turned by means of the mechanism.

The present invention contemplates a remote control system of the class described which is particularly useful where maintenance of calibration is indispensable, and therefore must be proof against a disturbance of the mutuality of angular disposition of the rotors of the transmitter and of the repeater. In Selsyn type systems heretofore it was of course common practice to provide manual or other means for varying the angular disposition of the rotor of the transmitter; but such means were usually operable both in the presence and in the absence of current within the circuit. Plainly mutuality of angular disposition of the two rotors may be easily lost when the circuit is open if such means are used. If the home station is out of sight of the distant station it is readily to be seen that at least two observers are required to correct the lost calibration. Also where such means are employed for varying the angular disposition of the rotor of the transmitter, and such means are subject to accidental or other undesirable use during deenergization, an indicator driven by the transmitter cannot be freely relied upon to show the angular disposition of the rotor of the repeater, and, where accuracy of result is essential, the system is, in fact, worthless. In a remote control system of the class described positive and reliable means for maintaining mutuality of the angular dispositions of the rotors of the transmitter and the repeater are indispensable if an indicator at the position of either Selsyn motor must invariably show, with absolute accuracy, the angular situation at the distant station.

It has been suggested in the general art of remote control systems involving the Selsyn apparatus that means be provided for preventing substantial variation of the angular disposition of the rotor of the transmitter during deenergization of the circuit. For example, it has been suggested that such means include the equivalent of a ratchet adapted to be engaged by a pawl when the circuit is open, the pawl being held out of engagement by a magnet, during energization, which is in circuit with the Selsyn motors. This arrangement does, in fact, provide a positive brake for preventing the rotor of the transmitter from being turned, when the circuit is open, more than a vary small amount of angular distance. But it may be seen at once that the very engagement of the pawl may operate slightly to destroy the precise mutuality of angularity of the two rotors by mechanically driving that of the transmitter a short distance out of alignment with that of the repeater. The pawl may operate as a brake only when the two Selsyns are out of electrical connection, and, of course, any movement imparted to the rotor of the transmitter cannot then be transmitted to the repeater. A repetition of the operation of the pawl may easily introduce a cumulative error that will eventually render the system useless even where the degree of accuracy of calibration required is relatively slight. Obviously if the undesirable features described above are present the control system is unsuited for precision work.

The remote control system of the present invention is particularly useful in connection with arts wherein absolutely accurate signaling of performance at a distant station is required to be available at a home control station. For example, the invention is specially adapted for use in connection with the art of photoengraving, wherein unusually heavy photographic equipment is common. Certain process and other cameras used in photoengraving are frequently so large that the rear of the stand of the camera is actually passed through the wall of a dark room where the photographer is normally located at the moment of the exposure. In camera installations of this type the diaphragm of the lens can be adjusted from the dark room only by blind means; and an extremely accurate signal is required to be available therein as to the character of the aperture of the diaphragm. Otherwise such blind means are practically worthless to the photographer who cannot check the actual condition of the aperture at the lens. Spoilage of plates is common in photoengraving as a result of disturbances of the calibration of a dark room indicator of the diaphragm condition. In installations where a Selsyn type transmitter drives a dark room indicator and a coupled repeater drives the diaphragm setting mechanism near the lens, and no means are provided for preventing turning of the transmitter rotor when the circuit is open, accidental loss of calibration may, and often does, occur repeatedly through accident, resulting in uncertain photography, unusable plates, and the eventual necessity of recovering calibration with the aid of two observers, one, of course, in the dark room to check the indicator, and the other outside to check the diaphragm.

Thus the remote control system of the present invention may be advantageously utilized in many connections wherein exact maintenance of calibration is essential.

These and other. features of the invention will be more fully understood from the following description and from the drawing, in which Fig. l is a schematic illustration of form of the remote control system wherein manual means are provided for turning the rotor of a transmitter, said means being connected to the rotor through a particular type of. magnetic clutch in circuit with the transmitter and a repeater. In this form the transmitter drives an indicator at the home station by means of a worm, and the repeater drives'mechanism, e. g., the ring. gear of a camera diaphragm, by means of a worm at a distant station.

Fig. 2 is a schematic illustration of a modification of the form described above. Herein the transmitter is driven directly by a motor at the home station, the motor being in circuit with the transmitter and repeater. The transmitter is shown here to drive an indicator, as above. The repeater and other parts located at the distant station are. not illustrated, but may be assumed to be as shown in Fig. 1.

Fig. 3 is a schematic illustration of a further modification of the form shown in Fig. 1. Here the regular indicator-driving transmitter is in couple with an auxiliary transmitter as well as with the repeater, illustration of the latter not being here duplicated. The two transmitters and the indicator are assumed to be located at the home station, and arrangement is shown whereby the auxiliary transmitter may be manually controlled. Ar rangement of parts at the distant station may be assumed to be as shown in Fig. 1.

Fig. 4 shows, schematically, another form of the system. Here a transmitter is worm connected to an indicator at the home station, and manual means for turning the rotor of the transmitter operate through a type of magnetic clutch different from that shown in Fig. l, the clutch, here, being also in circuit with the transmitter and the repeater. The repeater is shown to be worm connected to mechanism.

Fig. 5 shows a simple magnetic brake adapted positively for locking a rotary member, e. g., either or both Selsyn rotors, and at any angular disposition upon deenergization of a common circuit which is assumed to include the brake and Selsyns as well. Neither the transmitter or the repeater is here shown.

Fig. 6 shows, schematically, a further modification of the system wherein a transmitter is driven by a motor adapted also to drive what may be a distant mechanism, the motor being in circuit with the transmitter and also the repeater, this latter being assumed to be at a remote control station and being shown adapted to drive an indicator. A general control switch is shown to be located at this latter station. This arrangement is substantially the reverse of that shown in Fig. 2.

The form of the system illustrated in Fig. 1 shows that a ring gear, which may be that of the diaphragm of a camera of the class described above, is adapted to be rotated by means of a transmission train including a driver and an idler, the driver itself being actuated by means of a worm fixed on the rotor shaft of a Selsyn motor. All parts here are labeled, the Selsyn, a repeater, being designated X. These parts may be mounted on the lens board of the camera.

The repeater is coupled in usual manner with a transmitter, designated Selsyn Y. Those parts shown to the right in the figure may be assumed to be mounted within a' dark room, or'upon. a suitable ambulatory control unit which may be cableconnected with the repeater. Ob-

d viously those parts to the right in the figure may be situated at any convenient home station.

On the shaft 10 of the rotor of transmitter Selsyn Y is a worm; also mounted on shaft 10 is a disk A. Mounted on another shaft 11 is a disk B and a crank by means of which shaft 11 and disk B may be turned manually. Shafts 10 and 11' are parallel. Rotatably mounted on one end of a lever 12 at 13 is another disk C. All three disks are within a common plane. Lever 12 is pivotally mounted on any suitable support, not shown, at 14; and attached to its other end at 15 is a spring 16 which normally urges the lever to assume the position indicated here in dotted lines. The three disks are adapted to provide a frictional transmission train when the lever is in the position shown in solid lines. In the latter position disk C engages both disks A and B and interconnects them whereby turning of the crank operates to vary the angular disposition of the rotor of Selsyn Y.

Pivotally connected to the lever 12 at 17 is a link 18 which is also pivotally connectedat 19 to the core- 29 of a solenoid, the latter being shown to be in circuit withSelsyns X and Y.

Mounted on a shaft 21 being that of an indicator, as shown, is a spur engaging the worm upon the shaft of the rotor of Selsyn Y, the trans'rr'li'tte'r. I

When the common circuit is energized the core of the solenoid is retracted, swingingthe lever, against the urge of the spring, from the dotted line to the solid line position mentioned above. Thus when the circuitis deenergized the spring returns the lever to the dotted line position, thus breaking the frictional transmission train. Plainly, then, the crank may be utilized to control the rotor of the transmitter only when the circuit is energized; and accidental or other effort to use the crank'for adjusting the diaphragm before a control switch S is closed is ineffective. If the crank were mounted directly on the shaft of the rotor of Selsyn Y, and the magnetic clutching means were dispensed with, turning of the crankbefore closing of the control switch would result in immediate destruction of the calibration ofthe system; and

a reading at the indicator would bear no relationship to the actual condition of the diaphragm. Of' course, a subsequentclosing of the switch would not rectify the system, which would thereafter contain an error until somehow the calibrationwere restored.

It is also seen that the ringgear of the diaphragm cannot be utilized to vary the disposition of the rotor of the repeater, and that the indicator cannot be utilized to vary that of the rotor of the transmitter, due to the worms.

Fig. 2 illustrates a modification of the system; In thismodification the repeater station is assumed to' be as shown in Fig. 1, and the station is not redrawn. The transmittingstation is different from that of the form'of Fig. l in that in this modification a gearhead motor directly drives the transmitter, Selsyn Y, which in turn is worm connected to the indicator. The motor is in circuit with the transmitter and the repeater, thus'the motor cannot be utilized unless the Selsyns are in proper electrical couple.

Fig. 3 illustrates another modification of the system.- In this modification the repeater stationis assumedalso to be like that shown in Fig. l. The transmitting-station is different from that of the form of Fig '1 in that in this modification a third Selsyn-Z is included" inthe common circuit, said Selsyn being adaptedto be con trolled by a crank. The transmitter, Selsyn'Y, i's' worm connected to the indicator as also shown in Fig. 2. When the circuit is deenerg'ized' it is immaterialthat the crank of Selsyn Z be accidentally or otherwise turned,

for there can then be no-translation of the angular disposition of the rotor of Selsyn Z- to'Sels'yns X and Z.

Calibration between Selsyn Z and SeIsyhs X- and Y is ence of energization, the crank cannot be utilized to destroy the calibration of the indicator with respect to the diaphragm.

Fig. 4 shows a further modification of the invention. This modification comprises a Selsyn couple with a transmitter and a repeater, and a control switch S. To the right, in the figure, is seen a crank mounted on a shaft P which is coaxial with the shaft of the rotor of the transmitter. Mounted on the latter shaft is a worm for turning an indicator. The shafts are arranged to be coupled at Q by means of an electromagnetic clutch which is in circuit with the Selsyns. On the shaft of the repeater is a worm adapted to drive a mechanism K. The clutch is arranged to couple the shafts only upon energiza: tion of the common circuit. When switch S is open, as here shown, turning of the crank effects no rotation in the rotor of the transmitter. But upon energization the crank may be regarded as, in effect, mounted upon an extension of the shaft of the rotor of the transmitter, and may be used in usual manner to work the system. Thus in this modification premature turning of the crank with the switch open cannot destroy calibration of the system.

In a system including a Selsyn couple and worm driven mechanisms, as shown in Figs. 1 through 4, the worms themselves operate as locks to prevent a loss of calibration by improper handling of the mechanism, as, for example, in forms described above, it is impossible to adjust the ring gear of the diaphragm by hand and thereby vary the angular disposition of the repeater rotor, or to adjust the indicator by hand and thereby vary the angular disposition of the transmitter rotor. Within the scope of the invention it is plain that a clutch may be dispensed with altogether, and the worms as well may be avoided, if each Selsyn and its related mechanism are arranged to be positively braked against rotation in the absence of energization of the circuit. For example, a magnetic brake, such as illustrated in Fig. 5, there being one for the rotor shaft of each Selsyn, might well be used in such a modification of the invention. In Fig. 5 a disk D, in effect a brake drum, is shown mounted on the rotor shaft 22 of a Selsyn (not indicated). The shaft is assumed directly to drive a mechanism, whereby the mechanism cannot be moved independent of the Selsyn rotor. A brake shoe 23 is shown mounted on one end of the armature 24 of a solenoid 25. Between the shoe 23 and a face of the solenoid and surrounding said armature is a spring 26 normally forcing the shoe into braking engagement with the disk D and thereby locking the Selsyn rotor and its related mechanism against rotation in the absence of energization of the solenoid. The latter of course is assumed to be in circuit with the Selsyn couple. In the presence of energization the system is prepared for operation in proper manner. This modification provides, possibly, the most positive means for preventing accidental destruction of calibration within such a remote control system.

Fig. 6 illustrates an arrangement in which the system may be utilized for accurate control of distant machinery M requiring, for example, a motor other than a Selsyn for driving it. The drive motor of the machinery may, in this case, drive a Selsyn transmitter, the drive motor and the transmitter both being in circuit with a repeater at a home station wih a main swich S and an indicator I driven by said repeater.

Various modifications, all within the scope of the invention, will undoubtedly have been suggested by the foregoing. The gist of the hereindescribed remote control system is the prevention of loss of calibration due to premature attempts to employ the system in the absence of energization of the Selsyn couple. If the system is once properly calibrated careless handling thereafter cannot upset the calibration, and indications of apparatus performance and adjustment at distant stations may be relied upon with safety.

It will now be plain that the plicable in many industries and to camera controls.

I claim:

1. A plurality of Selsyns mutually in circuit; a plurality of mechanisms and a plurality of transmission means, each of said means including a worm, there being one mechanism and one transmission means for each Selsyn with each Selsyn driving its mechanism through its transmission means; means for driving a particular Selsyn rotor, said means being normally disconnected from said particular Selsyn rotor; and other means for connecting said second named means to said particular Selsyn only at the time said circuit is energized.

2. A plurality of Selsyns mutually in circuit; a plurality of mechanisms and a plurality of transmission means, each of said means including a worm, there being one mechanism and one transmission means for each Selsyn with each Selsyn driving its mechanism through its transmission means; means for driving a particular Selsyn rotor, said means being normally disconnected from said particular Selsyn rotor; and other means for connecting said second named means to said particular Selsyn only at the time said circuit is energized, said other means comprising an electromagnetic clutch in circuit with said Selsyns.

present invention is apis by no means limited References Cited in the file of this patent UNITED STATES PATENTS 1,650,626 Hewlett et a1. Nov. 29, 1927 1,868,523 De Florez July 26, 1932 1,909,815 De Florez May 16, 1933 2,042,280 Stuart May 26, 1936 2,368,300 Heist Jan. 30, 1945 2,393,189 Richmond Jan. 15, 1946 2,402,108 Willard June 11, 1946 2,406,550 Long Aug. 27, 1946 2,424,176 Kals July 15, 1947 2,489,689 Wald Nov. 29, 1949 2,579,476 Curry Dec. 25, 1951 2,589,834 MacCullum Mar. 18, 1952 2,642,554 MacCullum June 16, 1953 FOREIGN PATENTS 412,326 Germany Apr. 25, 1925 487,457 Great Britain June 14, 1938 

